In a known optical semiconductor package for packaging an optical semiconductor element such as a light-emitting diode (LED), an element mounting part is provided for mounting the optical semiconductor element and leads are provided for electrically connecting the optical semiconductor element to an external circuit. The optical semiconductor element is mounted on the element mounting part of the optical semiconductor package and the optical semiconductor element and the leads are wire bonded and then are molded with a transparent resin, so that a semiconductor light emitting device is formed.
FIG. 7 is a top view showing the external structure of an optical semiconductor package according to the related art. FIG. 8 is a sectional view showing the structure of the optical semiconductor package according to the related art, taken along line C-C′ of FIG. 7.
As shown in FIGS. 7 and 8, an optical semiconductor device having an optical semiconductor element mounted in the optical semiconductor package of the related art includes: a metal block 33 that has an optical semiconductor element 22 placed on an element mounting part on the major surface of the metal block 33 and is electrically connected to the optical semiconductor element 22 via a conductive adhesive 24; a lead 31 electrically connected to the optical semiconductor element 22 via a metal wire 26; a lead 32 electrically connected to the optical semiconductor element 22 through the metal block 33 by a metal wire 27; a light-transmissive member 16 that is made of a light-transmissive resin and covers the optical semiconductor element 22; and a base 14. The base 14 is made of a light-shielding resin. The bottom of the base 14 supports the inner leads of the leads 31 and 32 and the metal block 33, and the side of the base 14 supports the light-transmissive member 16. In this configuration, a region surrounded by the base 14, the inner leads, and the metal block 33 serves as a cavity region for mounting the optical semiconductor element 22. In the cavity region, the inner leads and the surface of the metal block 33 are coated with Ag to increase the reflectivity. In the optical semiconductor device of the related art, the metal block 33 has a backside region corresponding to a mounting region for mounting the optical semiconductor element 22 and the backside region penetrates the bottom of the base 14 and is exposed to the outside as a heat dissipation region (e.g., see Japanese Patent Laid-Open No. 2001-185763).